diff --git a/langgraph/serde/jsonplus.py b/langgraph/serde/jsonplus.py
index c6aa15184..e2e836689 100644
--- a/langgraph/serde/jsonplus.py
+++ b/langgraph/serde/jsonplus.py
@@ -8,8 +8,6 @@ from uuid import UUID
 
 from langchain_core.load.load import Reviver
 from langchain_core.load.serializable import Serializable
-from langchain_core.pydantic_v1 import BaseModel as LcBaseModel
-from pydantic import BaseModel
 
 from langgraph.serde.base import SerializerProtocol
 
@@ -37,14 +35,10 @@ class JsonPlusSerializer(SerializerProtocol):
     def _default(self, obj):
         if isinstance(obj, Serializable):
             return obj.to_json()
-        elif isinstance(obj, (BaseModel, LcBaseModel)):
-            # prefer non-deprecated method if available
-            if hasattr(obj, "model_dump"):
-                return self._encode_constructor_args(
-                    obj.__class__, kwargs=obj.model_dump()
-                )
-            else:
-                return self._encode_constructor_args(obj.__class__, kwargs=obj.dict())
+        elif hasattr(obj, "model_dump") and callable(obj.model_dump):
+            return self._encode_constructor_args(obj.__class__, kwargs=obj.model_dump())
+        elif hasattr(obj, "dict") and callable(obj.dict):
+            return self._encode_constructor_args(obj.__class__, kwargs=obj.dict())
         elif isinstance(obj, UUID):
             return self._encode_constructor_args(UUID, args=[obj.hex])
         elif isinstance(obj, (set, frozenset)):